An accumulating body of evidence suggests that chronic exposure to air pollution has detrimental effects on human health. However, very little is known about the effects of air pollution on neurological outcomes and almost no work has been done to determine if air pollution could contribute to risk of Parkinson disease. For the majority of PD patients, environmental factors are believed to contribute substantially to risk of disease and PD risk has been shown to be increased among persons exposed to pesticides, herbicides and agricultural chemicals, and decreased among tobacco smokers. The observed role of environmental factors such as pesticides and smoking in PD epidemiology suggests that exposure to environmental chemicals, such as those found in air pollution could also influence the risk of PD. This application includes a training plan and research component focused on training the candidate in environmental health research and in Geographic Information Systems (GIS) in order to study the association between exposure to air pollution and risk, mortality and progression of PD. The research project will use two large ongoing prospective cohort studies, the Nurses Health Study (NHS) and the Health Professionals Follow-up Study (HPFS) to examine the effects of PM10, PM2.5, PM10-2.5 as well as traffic air pollution on PD incidence, mortality and progression. The candidate will also study interactions between air pollution and dietary and lifestyle factors including smoking, intake of antioxidants, caffeine intake and use of NSAID anti-inflammatory medications. The chosen populations are ideal for this study because of their large size, long follow-up, prospective information on dietary and lifestyle factors, and the availability of geocoded addresses for the majority of the cohort participants, putting the candidate in a unique position to explore the impact of air pollution on PD. The training plan is focused on preparing the candidate for a career as an independent investigator in the field of environmental epidemiology of neurological disease, with a particular focus on GIS technology and PD. The training plan includes coursework in GIS and air pollution modeling, research seminars in environmental epidemiology and biostatistics, as well as private sessions with mentors and advisors, and travel to international meetings in both neurology and environmental epidemiology to present the results of proposed research.